Power transmission



July 18, 1944. ZIMMERMANN 2,353,802

' POWER TRANSMISSION Filed Dec. 12, 1940 I6 la 46 I L9 Fm. l

J 54- v S J EB 48 3a 30 I INVENTOR LUKAS ZIMMERMANN ATTORNEY Patented July 18, 1944 rowan 'rasnsmssrox Lukas Zimmermann, Detroit, Mich" asllgnor to Vickers Incorporated, Detroit, Mich, a corporation of Michigan Application December 12, 1940, Serial No. 369,813

. 5 Claims. (01. 103-1) This invention relates to power transmissions,

particularly to those of the type comprising two I gardless of the relative load distribution as be-- tween the two motors. In many applications of hydraulic power transmission systems, the parallel operation of two motors is desirable, but, as is well known, a simple parallel connection acts as a hydraulic differential and operates only the motor having the lightest load because the fluid delivered by the pump always seeks the path of least resistance. v

une such application is the retraction and extension of landing gear aboard aircraft. Commonly such retractable landing gear is operated by two independent cylinders, one for each of the two main landing wheels. It is highly desirable that these cylinders be operated from a single pressure source and that they move in synchronism regardless of the variations in effort as between the two cylinders.

It is an object of the present invention to provide an improved flow dividing unit which may be connected in two parallel circuits operating from a single point of supply and which with- Referring now to the drawing. the flow dividing unit comprises a pair of fluid pressure energy translating devices generally designated l0 and I2, each of which is identical in construction and only one of which will be described in detail. These units may be of any suitable type, the ones illustrated being similar to the device illustrated in the Thoma Patent No. 1,931,969. Thus, each device may comprise a driving flange ll rotatable upon anti-friction bearings l8 and having articulated thereto by ball joints a. plurality of connecting rods II which carry articulated pistons 20 on their opposite ends.

The pistons 20 are reciprocable in cylinders 22 of a rotary cylinder barrel 24 which is iour-' nalled on a stub shaft 26 by means of an antifriction bearing 28. The shaft 28 is mounted in avalve plate 30 having the usual annular pressure surface 32 in which the customary arcuate inlet and outlet ports 34- and 36 are provided. The cylinders 22 have cylinder ports 38 adapted to register alternately with ports 34 l and 38 during the revolution of the cylinder barrel.

A Garden shaft 40 having universal joints 42 at its opposite ends connects between the driving flange I4 and the cylinder barrel 24 to keep the two moving in synchronism.

A tubular casing 44 is bolted to the valve plate 30 and at its opposite end is provided withfan out significant throttling losses will serve to di-' vide the flow equally between the two parallel circuits.

A further object is to provide a device of this nature utilizing two fluid pressure energy translating devices of the axial cylinder type and to so connect the devices mechanically as to transfer both torque and internal piston thrust from either device to the other.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form of the present invention is clearly shown.

In the drawing:

Figure 1 is a side view partly in section of a flow dividing unit embodying a preferred form of the present invention.

Figure 2 is a top view partly in section of the unit illustrated in Figure Land showing diagrammatically a typical circuit in which the unit may be connected.

angularly disposed openingby which the casing is bolted to a common intermediate housing member 48 in which the bearings l8 are supported. A suitable drain connection at 48- be provided for draining internal leakage.

The driving flanges of the two units l0 and 12 are provided with mating serrated teeth III 'as shown in Figure .2 which couple the two driving flanges together in non-rotatable relation.

Thus, the-teeth provide a connection by which torque may be transferred between either drivingflange l4 and the other one. Immediately surrounding these serrated portions of the flanges is a common sleeve member I2 which is 'dowelled to one of the flanges as at 64 and which serves to hold the flanges a predetermined distance apart. It will be seen then thatthe sleeve I2 provides a connection between the flanges whereby the component'of piston thrust which is parallel to the axis of driving flange ll'f-niay be transferred directly from one flange to th other or vic ver Figure 2 illustrates diagrammatically a typical circuit in which the flow dividing device may be connected and comprising a pump 88 adapted to withdraw oil from a tank 58 delivering it through a delivery line 60 to a conventional fourway reverse valve 82. The usual relief valve 84 may be provided for bypassing the pump delivery to tank whenever a predetermined pressure is exceeded in the line 68. The tank return port of valve 82 is connected to tank by a conduit 68 having a branch 88 extending to the drain port .48 of the flow dividing device.

One of the cylinder portsof valve 82 is connected by a conduit 18 with the inlet port 34 of both devices In and I2. Conveniently this connection may be provided by means of a manifold 12 which is bolted by means of hollow sleeves 14 to each of the inlet ports I6 of the devices I and I2. The outlet port 18 if the right hand device connects by a conduit 88 with the lowerend of a fluid motor represented by a piston and cylinder 82. Similarly, the outlet port 18 of the device l2 connects by a conduit 84 with a motor 86. The opposite ends of motors 82 and 86 may be connected in parallel by means of a conduit 88 which leads to the other port of the reverse valve 62.

In operation, with the pump 56 running, it it is desired to move the pistons of motors 82 and 86 upwardly, the valve 62 may be shifted to direct pressure fluid from conduit 80 to conduit 18 where it flows to manifold 12 and inlet port 16 of both devices. A 7

Assuming for simplicity that the piston displacement of devices l8 and I2 is made equal and likewise that the displacement of motors 82 and 86 is equal and that they are desired to be moved at equal speeds, it will be seen thatthe fluid flowing in through inlet port 34- of each device will build up pressure on each of the pistons 20 which is in communication with the inlet port, and, due to the angular relation between the axis of barrel 24 and flange l4, the barrel and flange will start rotating in a counterclockwise direction as to the unit ID in Figure 2. The same action takes place at the unit l2, and the rotation will be in the same 4 direction, although, in the position illustrated in Figure 2, this rotation would appear as clockwise.

During this rotation the pistons move out of the cylinder bores while the cylinders are in communication with inlet port 34, and likewise, while they are in communication with outlet port 36, the pistons will niC-lg back into the cylinders, thus discharging oil to the outlet port 18 and through conduit 88 to the motor 82. Since the devices l and 12 are of equal displacement and since their driving flanges are nonrotatably connected together, it will be seen that equal quantities of oil will be passed through each device, thus pushing equal quantities of fluid into the lower end of motors 82 and 88. Accordingly, the pistons thereof will move upwardly in synchronism. discharging oil from the upper end through conduit 88 and back through valve 82 and conduit 66 to tank.

Should the load on the motor 82, for example, be in excess of that on the motor 88, a higher pressure will build up in conduit 88 than in conduit 84. This pressure will be reflected back through the device ill to the inlet port 18 and, since this is in free communication through manifold 12 with the inlet port of unit l2, the

same higher pressure will be imposed on the inlet of unit l2. This higher pressure will not be transmitted to conduit 84, however, because a portion of that pressure will be converted into torque applied to the driving flange of unit l2 and in turn transmitted to the driving flange of unit It. This in turn raises the pressure in the outlet port 18 so that the net effect is that the pressure in inlet manifold 12 will become stabilized at a. point midway between the pressure in conduit 80 and the pressure in conduit 84. In other words, as the fluid passes through unit l0, its outlet pressure is raised by torque applied from the unit i2. Likewise, in passing through the unit l2 the outlet pressure is reduced by the transfer of torque from unit [2 to unit l8. Regardless 'of the pressure diflerences, however, between conduits 80 and 84. the rate of flow therethrough will be equal at all times because the same quantity of fluid which passes through unit i0 must also pass through unit I 2 since they are mechanically coupled together.

Should it be desired to reverse the motion of the pistons of motors 82 and 88, the valve 62 may be shifted to its opposite position in which fluid is directed from delivery conduit 80 to conduit 88 and the upper end of the motors. The oil exhausting from the motors is carried separately to the ports 18 of the units to and i 2 which now become inlet ports and is exhausted through the ports 16, to manifold 12, conduit 10, valve 62 and conduit 66 to tank.

The synchronizing action under these conditions is analogous to that previously described,

the difference being that that motor which is under the least resisting load has an additional back pressure imposed on the lower end of the cylinder which pressure is caused by one device of the flow dividing unit building up torque to drive the other device thereof. This action is limited, however, by the amount of back pressure imposed on manifold 12 by resistance between it and the tank.

It will be noted that the present construction permits the use of considerably lighter bearings than are necessary in a single unit fluid pressure 5 energy translating device for the reason that the component of piston thrust parallel to the axis of the driving flange of unit I0 is substantially cancelled out by the opposite component transmitted from the flange of unit It through the sleeve 52. In this way the bearings l6 need only carry the radial load on the driving flanges l4 and may thus be considerably lighter than would otherwise be necessary.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form. it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: 1 V

1. A fluid regulating device for proportioning flow through a pair of conduits connected in parallel, comprising a pair of rotary fluid pressure energy translating devices of the type having a drive member. a, cylinders, pistons reciprocable therein, and motion converting means for converting reciprocation of the pistons into rotation of the drive member, each device having a pair of connection ports constituting aninlet and outlet for the device, means forming a conduit connecting one port of each pair, the other ports of each pair being isolated from each other, a housing forming a mounting for said devices with their drive members adjacent to and in alignment with each other, and means connecting said drive members, said plurality of axially positioned last means transferring both torque and thrust from either to the other of said drive members."

2. A fluid regulating device for proportioning flow through a pair of conduits connected in parallel, comprising a pair of rotary fluid pressure energy translating devices of the type having a rotatable cylinder barrel with axial cylinders, a driving flange rotatable on an axis inclined to that of the barrel and connecting rods articulated to the flange and to pistons reciprocable in the cylinders, each device having a pair of connection ports constituting an inlet and outlet for the device, means forming a conduit connecting one port of each pair, the other ports on each pair being isolated from each other, a housing forming a mounting for said devices with their driving flanges in coaxial alignment, and means connecting said driving flanges for conjoint rotation.

3. A fluid regulating device for proportioning flow through a pair of conduits connected in parallel, comprising a pair rotary fluid pressure energy translating 'devices of the type having a rotatable cylinder barrel with axial cylinders, a driving flange rotatable on an axis inclined to that of the barrel and connecting rods articulated to the flange and to pistons reciprocable in the cylinders, each device having a pair of connection ports constituting an inlet and outlet for the device, means forming a conduit connecting one port of each pair, the other ports of each pair being flow through a pair of conduits connected in parallel, comprising a pair of rotary fluid pressure energy translating devices of the type having a rotatable cylinder barrel with axialcylinders, a driving flange rotatable on an axis inclinedto that of the barrel and connecting rods articulated to the flange and to pistons reciprocable in the cylinders, each device having a pair of connection ports constituting an inlet and outlet for the device, means forming a conduit connecting one port of each pair, the other ports of each pair being isolated from each other, a housing forming a mounting for said devices with their driving flanges in coaxial alignment, anti-friction bearings for said drive flanges and substantially isolated from each other, a housing forming a mounting for said devices with their driving flanges in coaxial alignment, and means forming a non-rotatable connection between said flanges and adapted to transfer thrust from either flange to the other independently of the housing. 4. A fluid regulating device for proportioning smaller than necessary to carry the full thrust of piston reaction, and a sleeve member mounted between and rotatable with said flanges for' carrying the thrust from either member to the other.

v5. A fluid regulating device for proportioning 'flow through a pair of conduits connected in parallel, comprising a pair of rotary fluid pressure energy translating devices of the type having a drive member, a plurality of axially positioned cylinders, pistons reciprocable therein, and motion converting means for converting reciprocation of the pistons into rotation of the drive member, each device having a pair of connection ports constituting an inlet and outlet for the device,

means forming a conduit connecting one port of each pair. the other portsof each pair being isolated from each other, a housing forming a mounting for said devices with their drive members adjacent to and in alignment with each other, and means connecting said drive members.

LUKAS ZIlVllViERMANN. 

